High population differentiation of Okpe River Talbotiella gentii at Anum Boso, Ghana, uncovered by RAPD

Abstract

Talbotiella gentii Hutch. & Greenway is an endemic, severely threatened and fragmented species in Ghana. Though it is a highly valued non-timber product, it faces the threat of extinction from wildfire, and exploitation for charcoal and fuelwood, agriculture and building purposes. Efforts made by the Forestry Commission of Ghana to protect Talbotiella have focused on populations in reserves only while off-reserve populations are at the mercy of local farmers. The first updated data set of Talbotiella was collected in 2004. An entirely new Talbotiella population with about 197 trees near Okpe river and believed to belong to the river god was discovered at Anum Boso in the Eastern region of Ghana in 2006. Protection solely by the river god has safeguarded the population against wildfire, removal for fuelwood and charcoal production. Despite unique morphological characteristics that the population possesses, including tree size and height, no studies have been done on its genetic diversity. This study therefore investigated uniqueness in genotypes of the Okpe river Talbotiella population alongside four other best recorded genotypes of Talbotiella populations. Six out of 10 primers tested revealed 44 polymorphic bands. A PHIst value of 0.941 revealed by analysis of molecular variance (AMOVA) indicated limited gene flow and high risk of inbreeding among individuals. Squared Euclidean distances clearly showed that Okpe Talbotiella is closest to the best recorded genotypes and is therefore recommended for seed collection for conservation of Talbotiella in Ghana through in situ and ex situ methods.